According to me, the best place for eat Seafood, Fish & Shellfish at Salad Bar Buffet in Washington. Washington City also famous for BBQ Food or various Barbecue cuisions. I hope this information help you to reach your specific destination.
I think when you look at whats popular on a high end buffet would be Lobster, Crab legs and Salmon. A good raw bar and sushi station would also be good. The other would be a cocktail shrimp using 16-20 size shrimp or even using 15 and under shrimp. Your Poke idea is also a good idea. I also like a fresh Scampi demo station. Chef sliced Fresh Ahi ....Good luck
I've seen oysters, clams, shrimp, snow crab claws, Stone crab, lox, caviar with all the accompaniments, marinated octopus, conch, squid, Ceviche, all cold..along with salads of all kinds made from seafood and fish